Mixing characterisation of full-scale membrane bioreactors: CFD modelling with experimental validation

Membrane Bioreactors (MBRs) have been successfully used in aerobic biological wastewater treatment to solve the perennial problem of effective solids-liquid separation. The optimisation of MBRs requires knowledge of the membrane fouling, biokinetics and mixing. However, research has mainly concentrated on the fouling and biokinetics (Ng and Kim, 2007). Current methods of design for a desired flow regime within MBRs are largely based on assumptions (e.g. complete mixing of tanks) and empirical techniques (e.g. specific mixing energy). However, it is difficult to predict how sludge rheology and vessel design in full-scale installations affects hydrodynamics, hence overall performance. Computational Fluid Dynamics (CFD) provides a method for prediction of how vessel features and mixing energy usage affect the hydrodynamics. In this study, a CFD model was developed which accounts for aeration, sludge rheology and geometry (i.e. bioreactor and membrane module). This MBR CFD model was then applied to two full-scale MBRs and was successfully validated against experimental results. The effect of sludge settling and rheology was found to have a minimal impact on the bulk mixing (i.e. the residence time distribution).     

Monitoring and analysis of the energy cost of an MBR

Certain regions in the south of Europe are suffering an acute lack of water. One way to solve this hydric deficit is to use membrane bioreactors (MBR) to reuse the treated wastewater in tasks where drinking water is not required, e.g. irrigation. The aim of this research was to monitor physical-chemical (COD, BOD, and TN) and microbiological (EF, TC, and FC) parameters, as well as the energy costs in a Kubota MBR pilot plant located in Southeast Spain for one year, as well as to check the feasibility of the MBR process. The system showed a high robustness providing a fairly constant effluent with a large reduction of the entry pollutants and thus providing a highly reliable operation. High TSS, COD, BOD, NH⁺₄ and TN removal efficiencies up to 97, 94, 95, 98 and 81% respectively where achieved. The removal of the different microbials was quite high, with values in the permeate below 10 colony forming units (CFUs) most of the time. Some problems like blackouts, high temperatures and cleaning processes altered the normal operation lowering the retention of the different compounds and microorganisms. Regarding the energy consumption, two fluxes, 19 and 25 LMH were tested. Assuming a price for the electric supply of 0.0806 €/kW, the prices of the treated water for the two fluxes were 0.49 and 0.39 €/m3 and the total consumptions were 6.06 and 4.88 kWh/m³ for 19 and 25 LMH respectively. Aeration comprised almost 50% of the total energy requirements.     

MBR法在峨眉山垃圾填埋场渗滤液处理工程中的应用

在分析生活垃圾渗滤液水质特点的基础上,结合工程实例阐述了MBR工艺处理垃圾渗滤液的工艺流程、原理等,说明了MBR工艺处理垃圾渗滤液的特点和优势,经该工艺处理垃圾渗滤液可以达到国家排放标准,进而为我国生活垃圾填埋场渗滤液的咎置提供借鉴.     

A/O MBR处理城市污水回用的中试研究

采用中试规模(36 m3/d)的缺氧-好氧膜生物反应器(A/O MBR)对城市污水处理回用进行了试验研究.试验结果表明,该工艺处理效果优良,系统对COD、氨氮、浊度、细菌的平均去除率分别为94%,98.3%,99.6%,lg6,出水浓度分别为18 mg/L,0.65 mg/L,0.06 NTU,4个/mL.出水水质优于城市杂用水水质标准(GB/T 18920-2002).该系统具有较强的抗冲击负荷能力.     

FAT32文件系统的探究

通过对硬盘中逻辑结构的分析以及FAT32文件系统的数据存储方式的研究,总结了FAT32文件系统中各区域中数据的逻辑寻址过程。对在数据遭到逻辑破坏的情况下进行恢复有具有重要的参考价值。     

MBR的脱氮除磷工艺研究

采用厌氧/缺氧池/好氧MBR工艺处理模拟的城市生活污水,就系统主要的运行参数对氮磷去除的影响进行了研究.结果表明:TN、TP、NH3-N去除率分别达到80%、90%、95%以上,出水各项指标完全满足城市杂用水水质标准的要求.     

上海江桥生活垃圾焚烧厂渗滤液处理工程改扩建方案

在对江桥垃圾焚烧厂渗滤液处理工程的改扩建方案比选中,针对渗滤液的特性和现有的MBR工艺中的设施、设备运行现状,提出采用预处理-厌氧-好氧-MBR工艺.并充分考虑到了运行过程中已经出现或改造后可能出现的各种问题,提出了相应的解决措施.     

MBR工艺处理赖诺普利依那普利制药污水

应用接触氧化-MBR工艺处理制药废水,通过运行表明,该工艺高效稳定地去除了COD_(Cr)、BOD_5、SS,出水水质达到了国家《污水综合排放标准》(GB8978-96)二级排放标准。     

用MBR工艺处理印染前处理废水的试验研究

棉纺织印染前处理废水成分复杂、水质较差、处理难度较大。采用膜生物反应器(MBR)处理经过简单预处理的印染前处理废水,可使废水水质大为改善、后续处理压力大大减轻。在近100 d的现场试验中,得出了MBR的最佳操作参数为:温度25℃,HRT 18 h,MLSS 8 g/L,DO 2.8 mg/L,pH 7.5～8.5。在最佳工艺条件下,SS、色度、NH_3—N和COD_(Cr)去除率分别约为90%、30%、72%、72%。该工艺运行成本约为1.643元/m~3。     

太原循环经济环卫产业园固体废物污水处理厂工艺设计

为解决太原循环经济环卫产业园内生活垃圾焚烧处理处置、餐厨垃圾处理处置及其他固废处理处置过程中产生的高浓度废水处理问题,拟新建一座污水处理厂。设计处理规模为1 200 t/d,主要包括750 t/d的焚烧厂垃圾渗滤液和450 t/d的餐厨沼液。渗滤液处理采用"气浮+调节池+内循环厌氧反应器+两级A/O-MBR"的核心工艺,餐厨沼液处理采用"气浮+调节池+两级A/O-MBR"的核心工艺。污泥处理采用"离心脱水+热干化"工艺,处理后污泥含水率≤30%,干化污泥采用密封车辆送至焚烧厂焚烧处理。试运行结果表明,出水水质稳定达到设计标准。污水处理厂总投资为1.3亿元,污水处理直接成本为23.5元/t。